Estimated time line for BW 7.4 upgrade

Hi Experts,

My company is planning to upgrade from BW 7.1 EHP1 to BW 7.4 on Non-HANA (DB2) database. I am trying to find the time frame about BW specific activities in related threads but unable to get it. I went through some of the threads pasted below, but could not find any solid answer. Can any one of you give me an idea. How long BW activities takes place before and after technical upgrade if we have 3 system landscape. I will appreciate your help and time.

http://scn.sap.com/community/data-warehousing/bw/blog/2013/07/12/sap-bw-73-upgrade-issues-and-solutions

Technical Upgrade - SPDD & SPAU Phase

Please explain we what SPDD and SPAU are??

Thanks,

Shehzad